Posted
by
ScuttleMonkey
on Monday January 28, 2008 @04:15PM
from the not-time-to-duck-and-cover-just-yet dept.

jc42 writes "Astronomers have been looking at the first images of asteroid 2007 TU24, the 250-meter asteroid that will pass 540,000 km from the Earth at 8:33 UTC (3:30 EST) Tuesday morning. So get your telescopes out; it's a 10th-magnitude object. Or just hold your breath as the time approaches. It might be sobering to consider that it was just discovered last October, and we know about maybe half of the objects like this in Earth-crossing orbits."

they based it on the rate at which we find new ones compared to the volume of space and some other stuff. So it's a pretty good estimation. To estimate we found "all of them" we'd have to have not found any for like 500 years or something.

I don't really get what you're asking - we can determine about how many there should be. And apparently about half of those we are aware of. In another example, it would be naïve to assume we know about all the stars in the universe. We know what we can see, and can figure out how many there should be.

"We have good images of a couple dozen objects like this, and for about one in 10, we see something we've never seen before," said Mike Nolan, head of radar astronomy at the Arecibo Observatory. "We really haven't sampled the population enough to know what's out there."

If a house has five rooms, and after throughly searching one of the rooms you find two spiders, it's a reasonable guess that there are 10 spiders in the house. This is based on the assumption that the room you searched isn't "Jesus's magical spider room" but is in fact an average, typical room. The average number of spiders per room might be a little higher or a little lower than the one room you searched, but it wont be off by far. It's very unlikely that there are 100 spiders in all the other rooms, fo

But wouldn't it be more reasonable to assume that the spiders would be more numerous the closer you get to the mechanism by which they're able to enter your house? In that case, assuming you don't actually know how they're getting into the house, you could draw no conclusion at all from looking at just one room.

No, your analogy is terrible. Since this is Slashdot, what we really need in order to properly visualize this is a bad car analogy, thusly:

Let's say you're walking down a standard neighborhood street, and you count 5 cars parked on the side of the road. With this information, you can easily extrapolate out that if there are 50 other streets in your neighborhood, there must be 250 cars in the neighborhood that you haven't yet seen. Cars that you see actually moving down the street are just chaotic side effects of the car phenomenon, and can safely be discarded from the analysis.

Or, perhaps a more accurate, but still poor, car analogy: If scientists have scanned half the sky at random, and have discovered around 5,000 cars hurtling toward Earth, they can reasonably state that there are probably around 10,000 cars hurtling toward Earth at any given moment. However, even if they're completely wrong, it's probably best to keep an eye out for falling cars.

That is, if you consider roughly 66% a "reasonable" level of confidence. Of course, there's a bunch of fancy math that would use your given population of rooms and an unknown total population of spiders to better estimate the distribution of spiders across rooms. I find it easier to remember that, with one random sample of an unknown population, there's about a 2 in 3 chance that it's representative of the whole. Two samples that show up the same (two rooms surveyed, each with two spiders) should give yo

And yet imagine if you don't know how many rooms the building you're in has but in the room you are in you can see 400 people and at least 10 doors. You could assume that each door led to an identical room with 10 doors leading to 10 identical rooms and each room had 400 people in it.

Cut him some slack. He said "maybe half" which technically means you're not allowed to pin that down to an actual number. After all, this is the internet -- the magical place where, in lieu of hard facts, you can just make shit up.

The problem is that when you say something is 540,000km away, the huge general population tunes out. That's an ASTRONOMICAL number by most considerations, so nobody gives two shits. Except, as it turns out, we're dealing with astronomy, so astronomical numbers are the norm. The fact that nobody is really considering funding a worldwide effort to try and map all the objects that could potentially cause a major threat is disturbing. Hillary voted for $1 Million for a Woodstock museum - doesn't it make more sense to fund a huge, cheap project that could potentially help save the entire Earth from annihilation than a museum about a rockin' sex-fest? The latter doesn't really seem up most of congress' alley, but yet they vote that way.

NASA needs to spearhead projects that are useful, in collaboration with the rest of the space-viewing world. The fact that there isn't a loud voice shouting about this concept to the pols is embarrassing.

I was all set to make a point about how the hippies were right about just about everything - drugs are interesting, war is bad, love is good, we all need to lighten up a little or at least make getting blowjobs our top priority.

Google Asteroid Track!
You can spend enless processor cycles and unprecedented levels of optical goodness to search for world destroying asteroids yourself! If you find a world-killer, you get to name it after yourself!
(Damn, that fscking msheekhah killed the world!)

NASA needs to spearhead projects that are useful, in collaboration with the rest of the space-viewing world. The fact that there isn't a loud voice shouting about this concept to the pols is embarrassing.

What makes you think this isn't already happening? NASA already does this. On the national level, the US has the Near Earth Object [nasa.gov] program headed out of NASA's JPL. The Spaceguard Foundation [wikipedia.org] acts on the international level.

NASA has a fair number of other projects that are immediately "useful", as oppose

I can't compare to aerospace, but I can say that the current project of all NEO greater than 1km is nowhere near acceptable. I commend the NASA members who have said we need to catalog 90% of all objects greater than 140m in the next 30 years, but it doesn't go far enough. The Siberian explosion was from one less than half the diameter of that, with the one in the Mediterranean being only about 10m across (according to wiki [wikipedia.org]). We've gotten lucky with both of those but those were our two strikes. NASA and

The Siberian explosion was from one less than half the diameter of that, with the one in the Mediterranean being only about 10m across (according to wiki). We've gotten lucky with both of those but those were our two strikes.

Well, we're weren't unlucky with them. But considering that over 70% of the Earth's surface is water, and nearly half of that land surface is effectively unihabibited, missing a 15% chance twice in a row is still a better than 70% chance.

Charles Simonyi, (formerly of Microsoft), has donated $20 million, and Bill Gates (also formerly of Microsoft if memory serves) $10 million to help build the Large Synoptic Survey Telescope in Chile. The LSST is a super-widefield scope, expected to be able to survey the entire sky every three nights. One of its major uses will be early spotting of earth crossing asteroids.Total cost of the project is around 400 Million. The two donations above will fund three of the scope's main mirrors. Observations are ex

The problem is that when you say something is 540,000km away, the huge general population tunes out.

Then say something like "roughly 40 Earth diameters", which is something you can picture. Or maybe, "Imagine that the Earth were the size of an orange, this would be like a randomly fired bullet coming within thirteen feet of it."

If you wanted to make a point, you could say, "It's like living in a safe neighborhood that's a couple a blocks away from a street where there are regular drive by shootings, then h

I heard some astronomer dude on NPR today say that something this size is expected to come this close to earth about once every five years. So I fired up frink and got the following:( ( pi * ( earthradius ^ 2 ) ) / ( pi * ( (540000 km + earthradius) ^ 2 ) ) ) / 5 = 0.000027193886039087225468

At least this one is outside the lunar orbit. I seem to recall one a while ago that was much closer.

A quick Google says that lunar orbit is about 385 MM (mega meters), and this is 540 MM. (Why don't we use megameters when we're rounding to the nearest 1000 km? We have all these nice metric units; let's use them!)

Actually, mega meters should be abbreviated Mm. For some reason, staying metric doesn't seem to be popular in astronomical measurements--you drift off into AUs, light-years, parsecs. Nobody wants to use those gnarly large prefixes. It's only about 41 petameters to Alpha Centauri! And about 24 zettameters to Andromeda!

Yeah, another vote for "I hate it when people mess up metric prefixes." When you are talking about 1,000 or more of a kilometer, you should bump that up to a megameter. It doesn't matter if you round or not, but significant figures should be accounted for.

I don't know if you're serious or not but I've seen enough of people who actually think that a collision could be kept secret that I'll reply. Even if the all of the professional astronomers who've calculated the orbit of 2007 TU24 kept their mouths shut, there's still hundreds of amateurs out there who have the capability to measure this object's orbit with enough precision to know whether or not it's going to hit us. You wouldn't be able to get them to keep their mouths shut.

The first occurred in rural Russia, just like Tunguska, but the second one was in the Mediterranean, and had about the same power as the Nagasaki bomb (double Hiroshima). It could have easily struck a little to the north and hit highly populated Europe, or to the east and hit India/Pakistan, touching off a nuclear war there.

So far, we're failing the Civilization Intelligence Test in a really big way.

we have had events and observations that tell us that it will happen someday.

To say we have had 'warnings' implies there is some cosmic goat trying to tell us something. There is not, there is only a group of animals aware enough to consider long term and far away events and how they impacts us.

No, you're trying to add meaning to the word "warning" that I never explicitly or implicitly gave it in my prior post. A "warning" doesn't have to have intelligent origin. If you move to Kansas and see a bunch of tornadoes, it's a good idea to assume that more tornadoes may come in the future (after studying the issue and realizing it's because of the weather patterns and geography in that area) and prepare for them. It's not invalid to call those prior tornadoes can be called "warnings".

Is there anything that could be done to stop an impact if we were to see one coming? Aside from sending Bruce Willis up in a pair of Space Shuttles, of course. What's the value of having an accurate map?

Does anyone have a link to a page showing where the asteroid will be in the sky and at what time? Hopefully the clouds will clear here and I can get a glimpse of it through my telescope. I think 10x50 binoculars can only get you to magnitude 9, but I think my 8" dob can get me to 12th magnitude...

10th magnitude? A bit of a reach for my 90mm scope, especially with light pollution.

Forecast is cloudy with rain/snow. Won't see the sky anyway.

I live in Minnesota and it's January -- c-c-c-c-old!

2:30am CST on a weeknight? I have a job! That's past my bedtime.

I did catch an asteroid once, and it was kinda cool. Using a map of the asteroid's path, I set up the scope on some recognizable stars and waited for it. It looked like a faint speck moving against the background. Not sure it's worth the t